feat: add ParallelToolCalls to RunRequest

[kenshin54]

Describe the change
By default, parallel_tool_calls is set to true, which allows the llm to make multiple tool calls in one response. This can be opted out of with setting it to false, and ensures the llm only responds with one tool call at a time.

Provide OpenAI documentation link
https://platform.openai.com/docs/api-reference/runs/createRun#runs-createrun-parallel_tool_calls

Describe your solution
This PR added the same change as #787 , an any field ParallelToolCalls.

Tests
No new tests added.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.01%. Comparing base (774fc9d) to head (a6ca0b4).
Report is 47 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #847      +/-   ##
==========================================
+ Coverage   98.46%   99.01%   +0.55%     
==========================================
  Files          24       26       +2     
  Lines        1364     1418      +54     
==========================================
+ Hits         1343     1404      +61     
+ Misses         15        8       -7     
  Partials        6        6              

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[sashabaranov]

Thank you for the PR!